122 



THE SKELETON 



as far as the occipital protuberance. The grooves for the transverse (lateral) sinuses are 

 absent. 



The sphenoid in a macerated foetal skull falls into three pieces: (1) united pre- and post- 

 sphenoids, orbito-sphenoids, and lingulae, and (2 and 3) the ali-sphenoids. The pre-sphe- 

 noid is quite solid and connected with the ethmo-vomerine cartilage, and presents no traces of 

 the air sinuses which occupy this part in the adult skull. The pre-sphenoid bj^ its upper surface 

 forms part of the anterior cranial fossa, from which it is subsequently excluded by the growth 

 of the orbito-sphenoids. The optic foramina are large and triangular in shape. The lingulae 



Fig. 146. — The Occipital at Birth. 



J J.^VIl':A/lft»i('l,,-^^ 



Interparietal portion (develops in- 

 membrane) 



The interparietal and supra-occipital *^ 

 portions form the squamous portion 

 of the adult 



Supra-occipital portion (develops 

 cartilage) 



Ex-occipitaL 



Basi-occipital 



stand out from the basi-sphenoid as two lateral buttresses, and at the tuberculum sellae is the 

 basi-pharyngeal canal, which in the recent bone is occupied by fibrous tissue. The dorsum 

 sellae is still cartilaginous. The ali-sphenoids with the pterygoid processes are separated'from 

 the rest of the bone by cartilage. The foramen rotundum is complete, but the future foramen 

 ovale is merely a deep notch in the posterior border of the great wing, and there is no foramen 

 spinosum. The pterygoid processes are short, and each medial pterygoid plate presents a broad 

 surface for articulation with the lingula. The pterygoid canal is a groove between the medial 

 pterygoid plate, the lingula, and great wing. 



Fig. 147. — The Sphenoid at Birth. 



Lingula 



The temporal bone at birth consists of three elements, the petrosal, squamosal, and tym- 

 panic. The petrosal i)resents a large and conspicuous floccular fossa; the hiatus P'allopii is 

 a shallow bay lodging the geniculate ganglion of the facial nerve. There is a relatively large 

 mastoid antrum, but no mastoid process. The styloid process is unossified, but the tympano- 

 hyal may be detected as a minute rounded nodule of bone near the stylo-mastoid foramen. 

 The squamosal has a very shallow mandibular fossa and a relatively large post-glenoid 

 tubercle. The posterior part of the inferior border is prolonged downward into an uncinate 

 process {post-auditory process) which closes the mastoid antrum laterally. 



